patterns of inheritance- genetics

Question 1

define a gene

Answer 1

A length of DNA that codes for a single polypeptide or protein

Question 2

define locus

Answer 2

The position of a gene on a chromosome

Question 3

alleles

Answer 3

different forms of the same gene

Question 4

genotype

Answer 4

the alleles of a gene possessed by that individual.

Question 5

phenotype

Answer 5

observable characteristics of an organism
-determined by the expression of its genotype and the interaction of the environment on this:

Question 6

codominance + example

Answer 6

both alleles can be expressed in the phenotype at the same time
-e.g Allele A results in blood type A (IAIA or IAIO) and allele B results in blood type B (IBIB or IBIO)

Question 7

sex linked genes + example

Answer 7

-Some genes are found on a region of a sex chromosome that is not present on the other sex chromosome
-haemophilia

Question 8

2 main types of selection

Answer 8

Stabilising selection
Directional selection

Question 9

stabilising selection

Answer 9

natural selection that keeps allele frequencies relatively constant over generations unless there is a change in environment

Question 10

directional selection

Answer 10

-natural selection that produces a gradual change in allele frequencies over several generations
-due to selection pressure, etc

Question 11

genetic drift

Answer 11

when ‘chance’ affects which alleles get passed onto the next generation

Question 12

genetic bottle neck

Answer 12

-when a previously large population suffers a dramatic fall in numbers

Question 13

founder affect

Answer 13

-when only a small number of individuals from a large parent population start a new population